Forum Replies Created
-
Posts
-
I think that, if you look back at my posting, you will find that I don’t say that it is the worst. If Owen wants to defend that position, thats entirely up to him.
If asked an opinion, I would say it is much the same as all the others, only with a more UK slant in equipment choices. But thats hardly pouring praise on it! Some discussions will be sound and informed, some average, others will be hijacked by fools.
The net gave us access to more knowledge and with that came a greatly increased supply of gibberish. I think you will find that what I said can be summed up as “The advice may only be worth what you paid for it”.
I wish good luck to those of you who do help add quality to the fora and admire your tenacity, but find that what I have to do already fills my waking hours.
Also, I don’t think its sniping to point out that a source of information may be significantly suspect.
I don’t know about Owen, but I certainly find you have to take whats there with a large pinch of salt.
I just looked at a discussion in the deep sky section about whether M31 was a naked eye object and another in the imaging section on what affordable CCD camera to buy. Didnt exactly inspire confidence.
Looking more generally, there were postings from participants that were at best naive/lazy (even some with 20,000 posts), others who slavishly followed someones opinions because they had taken some nice pics and a few were clearly just plain biased in favour of stuff they had owned. I have no doubt it also has a percentage of observers who manage to “see” rather more than their instrument actually delivered and enjoy the immediacy of the applause available.
Personally, I couldnt say its worse than CloudyNights or any other fora but, while appreciating a proportion of participants will undoubtedly know their stuff, theres very much a need to be able to filter out the noise – and that can be difficult while you are yourself inexperienced.
You can understand Owen’s concern though, as (above) an experienced observer manages it twice in 30 years while using a 300mm Mewlon and some other very useful sounding instruments and yet its now being seen in scopes much smaller than that used to discover it. Yes, optics are better now and baffling has improved, but the MKI eyeball hasnt changed much (and mine could certainly do with an upgrade).
And I’m with him on newsgroups, sometimes the content is low quality.
Raises an important question about observing dim companions of bright stars.
Probably more convincing if it had also been unknown in the west at the same time.
Would love to see the artefact that proves them right.
Nice looking data. For those of us who are ignorant of all things RF, what is Moonbounce?
Also what sort of equipment did you need to accomplish such a good result?
The “Still Alive” signal should hit ground 15:39UT today together with a bunch of status telemetry. First results tomorrow hopefully.
Should be fun. An exciting time to be alive.
Did they also record changes in Mira? You would think that if they are paying attention that closely then they should have.
It says Henry Hatfield contributed observations. Would this be to the defunct BAA Section associated with artificial satellites, do you think?
Not arguing against DAOPHOT at all as I use it as part of a processing pipeline I have too.
Wouldnt say DAOPHOT is any more unfriendly than any other, merely that IRAF can be poorly documented and debugged. I find Starlink more robust, but as I wrote some of it, I would say that.
There is a version of DAOPHOT available for Python too – I always found IRAF as user friendly as a punch in the mouth and poorly debugged. The Python DAOPHOT seems to work okay for me. The major difference over the Fortran version is that it doesnt handle a bad pixel mask. Execution times similar (having no bad pixels to worrry about makes life lots easier).
I must admit I was under the impression DAOPHOT assumes a Gaussian profile so it can get unhappy with distorted images – theres a parameter for limiting how eccentric it will tolerate.
I did a quick study a year or two back and looked at Source Extractor, PISA and DAOPHOT. Each had its quirks. DAOPHOT was primarely aimed at stars while Source Extractor and PISA could do both stars and galaxy photometry. Source Extractor was very good but the documentation a little incomplete and PISA was by far the most memory efficient. When the source was star shaped they all did similarly in terms of the detections, but Source Extractor could use the WCS (I don’t think PISA did, but I might be wrong). Bottom line was they all had efficient detection approaches and if you already had code to handle the pixel space coordinate to Ra/Dec conversion, each was well worth having.
Source Extractor is available under Linux – and also in a limited form (no WCS support) under Windows. Would that or IRAF/Starlink be of any use for initial data extraction?
is there any chance the meeting will be recorded? I may be working that day…
I seem to have a knack for that.
It was a little hazy near Salisbury in Wiltshire but Astrometry.net is down so I am not sure which star is which. Will have a look later today. And with a 4×4 binned Starlight 694 doing the imaging I’ve only one image every 3 seconds. It was a chilly night.
Late addendum: From my location near Salisbury duration at least 191905.2-191908.0
Exposure 191855.0 – 191855.2 36593counts 178snr
Exposure 191858.0 – 191858.2 36114counts 176snr
Exposure 191902.0 – 191902.2 34820counts 170snr
Exposure 191905.0 – 191905.2 14824counts 78snr
Exposure 191908.0 – 191908.2 13304counts 69snr
Exposure 191911.0 – 191911.2 37475counts 181snr
Exposure 191914.0 – 191914.2 38728counts 187snr
With UK seeing being of the order of 3 arc secs its traditional to have pixels half that ie 1.5 arc sec across. The main worry I would have would be the vignetting, but if the flats are good and the guiding good then I don’t see it as a serious problem. I use a Celestron RASA and like the images that provides. Used with a Trius 694 it gives good clean results.
The only thing I have heard against hyperstars is the fun and games of collimating them, but for photometry rather that pretty pictures thats not a huge issue.
Do let us see some results…
I’m curious, why do you think it would be any worse than anything else? Theres possibly significant vignetting at the field edge and you ideally want a sensor where the pixels arent grossly undersampled, but otherwise its business as usual. 🙂
Any chance you could post examples from those corners please?
Perhaps the lens I borrowed previously was an outlier i.e. unusually good? In that the distortion was about 25% of the extent I found with my lens.
Could you post some excerpts from the corners please so we can compare?
Also, is it symmetric? Are all 4 corners similarly distorted?
Go to some observing meetings from your local society – they are not experts, they are ordinary people like you and me and are normally more than willing to show you what they do when they set up. It can’t be difficult or we wouldnt all be doing it.
Alternatively, if you have the means, a Meade LS scope does the trick. Place on level(ish) ground with a decent view of the sky, plug it in, make coffee, come back, start observing. It fails about 1 in 10 times.
No wizardry required. I borrowed one for 6 months and had a great time.
But long term, its better to learn than spend money up front.
